Saturday, August 27 2005 17:52 Hrs (IST) - World Time -

Part 1: Cancer- a general description

Cancer, The Word

Hippocrates, the ancient Greek physician, is credited with being the first to recognise the difference between benign and malignant tumours. The invasion of tumours so reminded him of crab claws that he called the disease karkinos, the Greek name for crab. In English this term survives as carcinoma. The English language also adopted the word cancer, which is the Latin word for crab. Single cancerous cell eventually becomes a microscopic collection of cells and ultimately begins to invade surrounding tissue.

What is a Tumour?

Each cancer runs its own distinctive course. In Leukaemia, the abnormal cells disperse throughout the body in the blood and bone marrow. With most cancers, a mass of cancer cells, called a tumour, begins to grow. Some tumours (particularly in children and young adults) may double their size in a month. Colon and lung tumours may require two months to double and some cancers take a year or more.

Most tumours are diagnosed when they are well advanced, with a mass of ten grams (approximately one-third of an ounce) or more than one billion cancer cells. These cells may invade tissues and spread throughout the body through the blood and lymph systems. A total body tumour burden of more than one kilogram (approximately two pounds) is usually not compatible with human life.

Cancer, The Definition

Every minute, ten million cells divide in the human body. Normally, cell division, accompanied by growth and specialised development, takes place in an orderly pattern. But when a cell becomes malignant, it acts in profoundly abnormal ways. Cancer develops from a single cell that has undergone mutations in its DNA (deoxyribonucleic acid), the genetic material that carries the body's hereditary instructions. Instead of maturing normally and dying, cancerous cells reproduce without restraint. It's not that they divide faster, but that they never stop dividing and they fail to mature. When removed from the body and placed in a laboratory dish with nutrients, they actually seem to be immortal.

Types of Cancer

Lung cancer is the number one cause of cancer deaths in men and women, with an average five-year survival rate of only 14 percent. Cancer of the colon and/or rectum, third in overall incidence and third in number of deaths each year, develops slowly and occurs most often in people over 50. Cancer of the prostate, the male gland which lies just below the bladder, has surpassed lung cancer as the most common site of cancer in men and is the second leading cause of cancer death in men.

At present rates, breast cancer (the most common site of cancer among females) will affect one out of every eight women. Invasive cancer of the cervix (the opening to the womb) and cancer of the endometrium (body of the uterus) account for more than eight percent of cancer cases in women. Most cases of skin cancer are highly curable, however, malignant melanoma can spread to other parts of the body very quickly. Once spread locally, the five-year survival rate is about 60 percent.

Leukaemia is diagnosed in about 30,000 people, children and adults each year. Causes are usually unknown. While five-year survival rates are still relatively low overall (42 percent), the past few decades have seen a dramatic increase in curability for one of the two major childhood types, acute lymphocytic leukemia.

Ovarian cancer is often 'silent,' showing no signs or symptoms until late in its development. Some families have a predisposition for ovarian cancer.

Part 2 Cancer- a general description